The present invention relates generally to a novel sensor housing and method of use thereof, and more particularly, to a pressure sensor housing and method of use thereof.
Pneumatically and electrically interfacing with a printed circuit board (PCB) mounted TO-8 pressure transducer is a recurring problem. Current solutions, interface TO-8 pressure transducers using two circuit boards in a stacked configuration. In order to manufacture the stacked configuration, manufacturing alignment/assembly issues force an expensive assembly process.
A side view of a prior art mounting configuration of a pressure transducer is shown in the diagram of FIG. 1. A standard size, i.e., TO-8, pressure transducer 10 is connected to a lower printed circuit board 12 and electrical leads 14 extend from the bottom of the pressure transducer 10 through lower board 12. Pressure transducer may be any known pressure transducer for generating a signal representative of a pressure sensed. The leads 14 may be attached to a lower surface 12A of the lower board 12, may be routed to an upper surface 12B of lower board 12, or may be connected to another board (not shown). In other embodiments, the leads 14 may not extend through lower board 12 at all, rather they may connect directly to the surface of lower board 12.
Pressure transducer 10 has a tube 16 extending upward, i.e., away from the upper surface 10A of transducer 10 and the upper surface 12B of lower board 12, for directing pressure to a sensing portion 18 of transducer 10. The sensing portion 18 is located within the radius of intersection of the tube 16 and the upper portion 10A of the transducer 10. Additional transducers may include additional sensing portions (not shown) to enable the transducer to provide differential pressure readings.
The upper end of tube 16, opposite transducer 10, is open to the pressure to be measured. The pressure to be measured includes a gas or liquid. The upper end of tube 16 extends through an upper printed circuit board 20 mounted (not shown) on lower board 12. The upper board 20 has an upper surface 20A and a lower surface 20B, respectively facing away from upper surface 12B of lower board 12 and facing toward the upper surface 12B of lower board 12. That is, upper board 20 is in a stacked configuration with lower board 12.
The upper end of tube 16 extends into a cavity 22 formed by housing 24 mounted on the upper surface 20A of upper board 20. The housing 24 is generally cylindrically shaped and includes a mounting points 26A, 26B for connection to the upper surface 20A. Housing 24 is typically bolted to the upper board 20 using bolts passing through upper board 20 and mounting points 26A and 26B. Pressure to be measured or monitored using transducer 10 is supplied to cavity 22 via a barb hook-up 28 (also referred to as a pneumatic connection) providing a passage into cavity 22. Barb hook-up 28 is a generally cylindrical shaped tube having a ridge 30 (shown more clearly in conjunction with FIG. 2) encircling the outside surface for retaining attached supply tubing (not shown). Typically, flexible tubing is used to supply a gas or liquid under pressure from a remote location to barb hook-up 28 and thus into cavity 22 for measurement by transducer 10.
The prior art or xe2x80x9ctwo-boardxe2x80x9d design is shown in a perspective view in FIG. 2 prior to assembly. Specific additional features viewable in FIG. 2 include a through-hole 31 for insertion of upper end of tube 16 through upper board 20 and into cavity 22, mounting through-holes 32A and 32B for receiving the mounting bolts securing housing 24 to upper board 20 via mounting points 26A and 26B, respectively, and ridge 30 on barb hook-up 28 for retaining supply tubing connected to the barb hook-up.
Also shown in FIG. 2 is central axis line C (dashed line) depicting the necessary alignment of lower board 12, transducer 10, upper board 20, and housing 24 for proper assembly. Each of the component parts must be aligned for assembly, e.g., the upper portion of tube 16 must be aligned with through-hole 31 and upper board 20 must be aligned with the mounting mechanism attaching it to lower board 12. Thus, multiple openings in the upper board 20 must be aligned for mounting to lower board 12. Misalignment of components increases the difficulty of assembly. Further, replacement or maintenance is made more difficult by having multiple parts to be aligned. Thus, there is a need in the art for a simpler pressure sensor housing mounting configuration to reduce or eliminate alignment issues.
Somewhat relatedly, due in part to the alignment issues described above and because of the multiplicity of component parts involved, the two-board design requires a longer assembly time than a single board design. Thus, there is a need in the art to reduce the assembly time required for a pressure sensor housing configuration. Further, because assembly is simplified with a single-board design, there is no additional specialized tooling required for assembly. With a two-board design, additional special tools are needed to ensure proper alignment of upper board 20 over lower board 12, housing 24 on upper board 20, and tube 16 inside housing 24 and upper board 20. Once aligned, the piece parts need to be attached to one another, as well. Thus, there is a need in the art to eliminate the necessity of special tools for assembly. In conjunction with a reduction in the number of tools required and a simplified alignment process, an important by-product is the reduction of the amount of mounting hardware required for assembly. This reduces the cost and complexity of the assembly process. Thus, there is a need in the art for a sensor housing configuration requiring a reduced amount of mounting hardware.
Necessarily also, the amount of assembly-induced rework due to errors in assembly is increased because of the complicated nature of the two-board design. More component parts are handled, moved, and removed increasing the possibility of errors and/or breakage of components. Thus, there is a need in the art to reduce assembly-induced rework in the sensor housing configuration.
Further, in the two-board design it is difficult to test the individual component parts prior to assembly because the entire configuration must be assembled for a test.
That is, the housing 24 must be mounted to upper board 20 which must be attached to lower board 12 which must have the transducer 10 mounted thereon. Therefor, there is a need in the art for a mounting configuration more conducive to testing of components prior to assembly.
It is therefore an object of the present invention to provide a simpler pressure sensor housing mounting configuration to reduce or eliminate alignment issues.
Another object of the present invention is to provide a mounting configuration more conducive to component-level testing prior to assembly.
Still another object of the present invention is to reduce the assembly time required for a pressure sensor housing configuration.
Further still, another object of the present invention is to eliminate the necessity of special tools for assembly.
Another object of the present invention is to provide a sensor housing configuration requiring a reduced amount of mounting hardware.
Still another object of the present invention is to reduce assembly-induced rework in the sensor housing configuration.
The above described objects are fulfilled by a pressure transducer including a tube for measuring pressure and leads for providing signals indicated of the measured pressure is mounted to a printed circuit board. A housing including elongated mounting portions or legs taller than the pressure sensor transducer and a cavity for receiving the tube is mounted over the pressure transducer to the printed circuit board. The housing is connected to the printed circuit board using the elongated mounting portions. A pneumatic connection to the housing provides a pressure to be measured to the cavity and thence to the pressure transducer tube.
An apparatus aspect of the pressure transducer mounting configuration includes a printed circuit board, a pressure transducer mounted on the printed circuit board, and a housing surrounding the pressure transducer on a side of the printed circuit board. The housing is mounted to the printed circuit board. A further embodiment includes a pressure transducer having a tube for receiving pressure to be measured by the pressure transducer and the housing further includes a cavity for providing the pressure to the pressure transducer and a sealing ring for receiving and sealing the tube of the pressure transducer in the cavity open to the pressure.
An apparatus aspect of the housing includes a central and generally cylindrical portion having (a) a central cavity open at the bottom of the cylindrical portion and (b) two elongated mounting portions connected at opposing locations along the bottom of the outside surface of the longitudinal cylindrical portion and long enough to extend above a pressure transducer when the bottom edge of the mounting portions are mounted on a printed circuit board. The housing further includes a pneumatic connection connected to a through-hole in the side of the longitudinal cylindrical portion and opening to the central cavity for providing pressure. A further embodiment of the housing includes a sealing ring located within the central cavity and adapted for sealing around a tube inserted into the open bottom of the central cavity.
A method aspect of mounting a pressure transducer housing on a printed circuit board includes mounting a pressure transducer to the printed circuit board and mounting a housing to the printed circuit board. The housing surrounds the pressure transducer on a side of the printed circuit board and provides a pressure to be measured to the pressure transducer. In a further embodiment the method includes a pressure transducer including a tube for receiving the pressure to be measured and a housing including a cavity for receiving the tube and providing the pressure to the transducer.
Still other objects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein the preferred embodiments of the invention are shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description thereof are to be regarded as illustrative in nature, and not as restrictive.